Adjustable screed

ABSTRACT

An improved screed for contouring cementitious material around a central drain is described. The screed includes a drain pivot element adapted and constructed to be rotatably secured in a drain depression. An elongated material contact element adapted and constructed to uniformly contour the surface of cementitous material is provided. A height adjustment element connects the drain pivot element to the material contact element. The height adjustment element is used to set the operating height of the material contact element, the drain pivot element is secured to the drain, and the material contact element is placed in contact with the cementitious material and rotated to contour the material surrounding the drain into a uniform, generally frustoconical configuration generally concentric with the drain.

CROSS-REFERENCE TO RELATED APPLICATION

None.

BACKGROUND OF THE INVENTION

According to Lambert and MacDonald in their 1998 monograph titled “Reinforced Concrete—History, Properties & Durability” (published by the Corrosion Prevention Association, Surrey, U.K.), the oldest known surviving concrete is to be found in the former Yugoslavia and was thought to have been laid in 5,600 BC using red lime as the cement. The first major concrete users were the Egyptians in around 2,500 BC and the Romans from 300 BC. The Romans found that by mixing a pink sand-like material, which they obtained from Pozzuoli, with their normal lime-based concretes they obtained a far stronger material. The pink sand turned out to be fine volcanic ash, and they had inadvertently produced the first ‘pozzolanic’ cement. Pozzolana is any siliceous or siliceous and aluminous material which possesses little or no cementitious value in itself but will, if finely divided and mixed with water, chemically react with calcium hydroxide to form compounds with cementitious properties.

The Romans made many developments in concrete technology including the use of lightweight aggregates as in the roof of the Pantheon, and embedded reinforcement in the form of bronze bars, although the difference in thermal expansion between the two materials produced problems of spalling. It is from the Roman words ‘caementum’ meaning a rough stone or chipping and ‘concretus’ meaning grown together or compounded, that we have obtained the names for these two now common materials.

Since the Romans had no powered cement mixers, they prepared small batches of concrete, and layered these batches either between wooden forms, or between facings of stone or brick already assembled. The Roman practice of pouring liquid concrete into wooden forms was rediscovered by the architect Bramante in the 15th century A.D., and incorporated into his early work on the Cathedral of St. Peter in Rome.

It was also in Roman times that cementitious materials were used for structures, such as baths, having central drainage systems. The floors of these structures slope towards the drain by applying a straight element, called a screed, to the material prior to setting. In one common technique, one end of the screed is placed in the drain, and the screed is rotated around the drain in the shape of an inverted frustocone.

Not surprisingly, various mechanisms for forming drains in concrete floors and associated systems have found their way into the patent literature. For example, U.S. Pat. No. 6,568,140 to Kirby concerns an apparatus and method for making a sloped floor including a plurality of elongate arms disposed in radial array relative to a drain. Each arm has a common height along its extent. The radially innermost end of each arm is positioned near or connected to the drain. In a first embodiment, the radially innermost end of each arm is pivotally connected to an adapter that is connected to a center ring that circumscribes the drain. In a second embodiment, each arm is positioned at an incline by an adapter that rigidly joins the arm to the center ring. In a third embodiment, the arms are of shallow construction and are removed after the concrete has been poured. A mounting strip secured to the shower wall may support the radially outermost end of each arm. In all embodiments, the concrete is worked so that it is flush with the uppermost edge of each elongate arm.

U.S. Pat. No. 6,848,229 to Rossi deals with apparatuses and methods for shaping a graded surface of a fill material around a drain. The apparatus provides an outer ring for positioning within a shower enclosure, an inner ring for positioning within the outer ring and around the drain, a rail assembly connected at each of two ends to the outer ring, and a carriage connected to the rail assembly and the inner ring. Each of the inner ring and outer ring provides a top edge to which the surface of the fill material can be brought flush.

U.S. Pat. Nos. 6,088,984 and 6,155,015, both to Kirby, show a method for making a floor that slopes toward a drain that includes the steps of enclosing a predetermined area of a flat support surface around the drain with upstanding border members, positioning an annular ring in closely spaced, concentric relation around the drain, arranging a plurality of straight form members in radial relation to the drain, connecting a radially innermost end of each form member to the annular ring so that the top edge of each form member is spaced downwardly from the plane of the drain by a distance equal to a tile thickness, and positioning an outermost end of each form member in abutting relation to the border member. Each form member has a height at its innermost end that is less than a height of its outermost end. A cementitious material is poured into the predetermined area and the material is made flush with the respective top edges of the form members. An auxiliary form member is attachable to a trailing end of each form member to increase the versatility of the method. In an alternative embodiment, the form members are self-supported by laterally-extending legs or manually held in place until the cementitious material is poured so that the annular ring is not needed.

U.S. Pat. No. 6,886,190 to Tompane describes an apparatus and method for aligning the exposed drain in finished surfaces in construction with the underlying drains and conduits of the construction infrastructure. The device features an inner generally planar center section, preferably round, with an off center drain aperture communicating between a top surface and a bottom surface. The center section is rotatable in a similarly shaped aperture formed in the surface material surrounding the underlying drain which can also be formed in a surrounding tile to be placed over the drain or in the finished material itself. Once the off center drain aperture is aligned with the underlying drain with the perimeter of the center section aligned with the aperture in the surrounding material, the center section is placed into the similarly shaped aperture and fixed in position with adhesive or grout and the drain strainer may be mounted into the off center drain aperture. The device may be pre manufactured in separate components, kits of separate components, or may be formed using a method of making the components from the tile or finished surface being laid.

U.S. Patent Publication No. 20080184480 to Adelman is directed to a variable length arm and devices to locate the inner end and outer end of the arm to set the slope of a pre-slope floor and to set the thickness of a base floor to receive tile. The variable length arm and devices are used in a method to create the floor.

U.S. Patent Publication No. 20070256393 to Black discloses an apparatus for creating a sloped surface comprising at least one leveling member and at least one guide member for guiding the at least one leveling member. The at least one leveling member changes the slope of the surface depending on a distance between a point of low elevation to a point of higher elevation as the at least one leveling member travels across the at least one guide member.

U.S. Patent Publication No. 20060034663 to Lampley is directed to a diamond trowel blade with diamond particles that will attach to a power trowel for surface preparation of hardened concrete surfaces. The diamond trowel blade includes a diamond bearing surface, for preparing the concrete surface; a backing plate for supporting the diamond bearing surface; and a mounting arm for attaching the trowel blade to the power trowel. A method for mechanically preparing a concrete surface with a diamond trowel blade attached to a power trowel is provided. The method includes the surface preparing steps of; selecting the diamond trowel blade with the appropriate grit for the concrete surface, installing the diamond trowel blades on the power trowel, and directing the rotating diamond trowel blade over the surface until the smoothness is attained for the particular grit in use; and repeating the steps until the user achieves the smoothness desired.

It can be seen from the foregoing that the need exists for a lightweight screed having a measurably adjustable height setting mechanism.

SUMMARY OF THE INVENTION

An improved screed for contouring cementitious material around a central drain is described. The screed includes a drain pivot element adapted and constructed to be rotatably secured in a drain depression. An elongated material contact element adapted and constructed to uniformly contour the surface of cementitous material is provided. A height adjustment element connects the drain pivot element to the material contact element. The height adjustment element is used to set the operating height of the material contact element, the drain pivot element is secured to the drain, and the material contact element is placed in contact with the cementitious material and rotated to contour the material surrounding the drain into a uniform, generally frustoconical configuration generally concentric with the drain.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

FIG. 1 illustrates a perspective view of an embodiment of a screed in accordance with the principles of the present invention.

FIG. 2 illustrates a sectional view taken along lines 2-2 of FIG. 1.

FIG. 3 illustrates a side elevational view of the embodiment of FIG. 1.

FIG. 4 illustrates a detailed perspective exploded view of a height adjustment mechanism constructed in accordance with the principles of the present invention.

FIG. 5 illustrates a detailed perspective exploded view of a portion of the height adjustment mechanism.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent that the invention may be practiced without these specific details. Without departing from the generality of the invention disclosed herein and without limiting the scope of the invention, the discussion that follows will refer to the invention as depicted in the drawings.

An embodiment of a screed 10 in accordance with the principles of the present invention is shown in FIGS. 1-3. The screed 10 includes a drain pivot element 12 adapted and constructed to be rotatably secured in a drain depression D, such as a drain pipe or drain fixture associated with a floor drain. An elongated material contact element 14, adapted and constructed to uniformly contour the surface of cementitous material, extends from the drain pivot element 12. The drain pivot element 12 and material contact element 14 can be fabricated from any suitable rigid, durable, lightweight, and inexpensive material. Preferably, the drain pivot element 12 and material contact element 14 are formed of a non-corrosive metal. In the illustrated embodiment, the drain pivot element 12 and material contact element 14 are fabricated from aluminum, either machined aluminum or rectangular aluminum tubing having a rectangular cross-section. The material contact element 14 can be any suitable length. For example, a two (2) foot length can be chosen for the material contact element 14. A plastic end closure cap 16 provides a seal and protective closure for the material contact element 14. At the opposite end of the material contact element 14 an end plug 17 closes the opposite end of the material contact element 14 and provides an interface with the drain pivot element 12 as will be described in detail below.

The drain pivot element 12 is connected to the material contact element 14 via a height adjustment element 18. The height adjustment element 18 is provided with indicia 20 corresponding to desired height settings, here illustrated as occurring at ⅛″ increments. The height adjustment element 18 includes a tab 22 extending from the drain pivot element 12. A groove 24 is formed in the end plug 17 of the material contact element 14. The groove 24 corresponds in size and configuration to the tab 22 to slidingly receive the tab 22.

A securing mechanism 26 extends through the tab 22 and the groove 24. The securing mechanism 26 includes a threaded rod 28 extending through a bore 30, provided in the end plug 17 of the material contact element 14, which in turn extends through the tab 22 and slot 32. The rod 28 engages a threaded insert 34 at a terminal end of the bore 30. A fluted knob 36 is secured on the threaded rod 28 at an end opposite to the threaded insert 34 of the bore 30. A flexible boot 38 seals the bore 30 at a location adjacent to the fluted knob 36.

In operation, loosening of the rod 28 via the knob 36 causes the adjustment element 18 to permit height adjustment of the material contact element 14. Once the desired height is achieved, the knob 36 is used to tighten the adjustment element 18 and set the operating height of the material contact element 14. As illustrated in FIG. 5, the material contact element 18 preferably includes a horizontal slot 40. The slot 40 improves operation of the device 10, since when you screw the knob 36 tight it causes the metal or plastic, depending on the material used, to bend inwardly and clamp against the male end 22 of the adjustment element 18. The slot 40 will hold the adjustment element 18 to the material contact element 14 in a more secure and stabilzed fashion.

The drain pivot element 12 is then secured to the drain, and the material contact element 14 is placed in contact with the cementitious material and rotated to contour the material surrounding the drain into a uniform, generally frustoconical configuration generally concentric with the drain. The height adjustment allows accurate contouring of the depth of the cementitious material to accommodate the height of any flooring material to be applied to the floor surrounding the drain.

While this invention has been described in connection with the best mode presently contemplated by the inventor for carrying out his invention, the preferred embodiments described and shown are for purposes of illustration only, and are not to be construed as constituting any limitations of the invention. Modifications will be obvious to those skilled in the art, and all modifications that do not depart from the spirit of the invention are intended to be included within the scope of the appended claims. Those skilled in the art will appreciate that the conception upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

The invention resides not in any one of these features per se, but rather in the particular combinations of some or all of them herein disclosed and claimed and it is distinguished from the prior art in these particular combinations of some or all of its structures for the functions specified.

With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, including variations in size, materials, shape, form, function and manner of operation, assembly and use, and all equivalent relationships to those illustrated in the drawings and described in the specification, that would be deemed readily apparent and obvious to one skilled in the art, are intended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 

1. An improved screed for contouring cementitious material around a central drain, the screed comprising the following: a drain pivot element adapted and constructed to be rotatably secured in a drain depression; an elongated material contact element adapted and constructed to uniformly contour the surface of cementitous material; and a height adjustment element connecting the drain pivot element to the material contact element; whereby the height adjustment element is used to set the operating height of the material contact element, the drain pivot element is secured to the drain, and the material contact element is placed in contact with the cementitious material and rotated to contour the material surrounding the drain into a uniform, generally frustoconical configuration generally concentric with the drain.
 2. A screed in accordance with claim 1, wherein the height adjustment element further comprises indicia corresponding to desired height settings.
 3. A screed in accordance with claim 2, wherein the indicia of the height adjustment element are placed at ⅛″ increments.
 4. A screed in accordance with claim 1, wherein the drain pivot element and the material contact element are fabricated from aluminum tubing having a rectangular cross-section.
 5. A screed in accordance with claim 4, wherein the drain pivot element further comprises a first plastic end closure cap.
 6. A screed in accordance with claim 5, wherein the material contact element further comprises a second plastic end closure cap.
 7. A screed in accordance with claim 1, wherein the adjustment mechanism comprises: a tab extending from the drain pivot element; a groove in the material contact element, the groove corresponding in size and configuration to slidingly receive the tab of the drain pivot element; and a securing mechanism extending through the tab and the groove.
 8. A screed in accordance with claim 7, wherein the adjustment mechanism further comprises: a bore through the material contact element; a threaded insert at a terminal end of the bore; and a vertical slot formed through the tab adjacent to the bore.
 9. A screed in accordance with claim 8, wherein the securing mechanism comprises a threaded rod extending through the bore and the vertical slot to engage the threaded insert.
 10. A screed in accordance with claim 9, wherein the securing mechanism comprises a fluted knob secured on the threaded rod at an end opposite to the threaded insert of the bore.
 11. A screed in accordance with claim 9, further comprising a flexible boot sealing the bore at a location adjacent to the fluted knob.
 12. An improved screed for contouring cementitious material around a central drain, the screed comprising the following: a drain pivot element adapted and constructed to be rotatably secured in a drain depression; an elongated material contact element adapted and constructed to uniformly contour the surface of cementitous material; and a height adjustment element connecting the drain pivot element to the material contact element; whereby the height adjustment element is used to set the operating height of the material contact element, the drain pivot element is secured to the drain, and the material contact element is placed in contact with the cementitious material and rotated to contour the material surrounding the drain into a uniform, generally frustoconical configuration generally concentric with the drain, and wherein the adjustment mechanism comprises a tab extending from the drain pivot element, a groove in the material contact element, the groove corresponding in size and configuration to slidingly receive the tab of the drain pivot element; and a securing mechanism extending through the tab and the groove.
 13. A screed in accordance with claim 12, wherein the adjustment mechanism further comprises: a bore through the material contact element; a threaded insert at a terminal end of the bore; and a vertical slot formed through the tab adjacent to the bore.
 14. A method for contouring cementitous material comprising the steps of: placing a drain pivot element of a screed in a central drain; adjusting the operating height of a material contact element of the screed with an integral height adjustment mechanism; and pivoting the screed about the central drain. 